For incorporating liquid surfactant compositions, in particular washing or cleaning agents, either those ingredients that dissolve in the liquid phase of the agent or those that can be accordingly homogeneously suspended in an undissolved manner are available. For insoluble ingredients, a stable, homogeneous suspension is required for the function and aesthetics of the washing or cleaning agent. Sedimented solid particles may clump together and, when used, may lead to local excess concentrations of the ingredient and thus to uneven dosing per wash load. In addition, visible clumps, greasy deposits or residues of the solid ingredient on an, e.g., transparent wall of the storage container are not aesthetically pleasing.
Certain, optionally dyed, solid particles, which are visible to the naked human eye in suspension in a, transparent or translucent, liquid phase as individualized particles and are incorporated, are often referred to as speckles. For this purpose, corresponding particles have an appropriate particle size and are aesthetically attractive to the consumer. Microcapsules are also solid ingredients and include any type of capsule known to a person skilled in the art, but in particular core-shell capsules and matrix capsules. Matrix capsules are porous shaped bodies that have a structure similar to a sponge. Core-shell capsules are shaped bodies that have a core and a shell.
However, all of these solid particles, in particular the speckles, tend towards sedimentation in liquid surfactant compositions.
The sedimentation of particles out of the suspension is usually prevented by the use of surfactant compositions having a yield point. A yield point can be produced by selecting specific surfactant combinations, usually in the presence of an electrolyte salt, by establishing a lamellar phase. It is also conceivable to use selected polymer thickeners for producing a yield point.
In particular, it is difficult to provide surfactant compositions having a high surfactant concentration with a yield point in the range of from 0.01 to 5 Pa. By using lyotropic liquid-crystalline mesophases, an excessively high yield point is usually achieved at a high surfactant concentration. In such a case, the flow behavior is inhomogeneous (what is known as “clumpy” flow). Furthermore, an excessively high yield point results in the suspended particles adhering to the wall of the storage container for the surfactant composition. If polymer thickeners are used to form the yield point, at a high surfactant concentration this is sometimes achieved by using a very high quantity of the polymer thickener, and often is not achieved at all. Large quantities of thickener impair the cleaning performance of surfactant compositions, and in textile treatment this can in particular additionally result in graying of the textile.